The present invention relates generally to precision alignment of one or more parts on a common carrier. More specifically, the present invention relates to a self-aligned common carrier including a carrier substrate having a predetermined crystalline orientation and a pocket formed in the carrier substrate by etching a surface of the substrate along a predetermined crystalline plane. A chip having a surface thereof etched along an identical crystalline plane is mounted to the carrier substrate by inserting the chip into the pocket. The crystalline planes are complementary to each other thereby resulting in near perfect self-alignment between the chip and the carrier substrate.
Articles and publications set forth herein are presented for the information contained therein: none of the information is admitted to be statutory xe2x80x9cprior artxe2x80x9d and we reserve the right to establish prior inventorship with respect to any such information.
It is well known in the art to use an inkjet printer for applications that require a hardcopy printout on a sheet of media. For example, it is commonplace to use an inkjet printer to print on sheets of paper, transparencies, labels, and the like. In a typical inkjet printer, a carriage holds one or more ink cartridges. Each cartridge has an inkjet printhead (pen) that includes several nozzles from which ink is ejected in a direction that causes the ink to impinge on the sheet of media. Typically, the carriage must travel across the media so that each pen can reach the full area of the media. The media to be printed on is usually driven along a media axis of motion and the pen is driven along a carriage axis of motion that is perpendicular to the media axis. In color inkjet printers, two or more cartridges are needed to print color images. For instance, a color inkjet printer can have four cartridges (black, cyan, magenta, and yellow) with a pen for each color. Consequently, in a four cartridge printer, the carriage must travel the width of the media, plus the width of the four pens, plus the space between pens. Therefore, the width of the inkjet printer is determined to a large extent by the distance the carriage must travel in order to print images on the full area of the media. For example, in an inkjet plotter, the carriage may have to travel a distance greater than the width of a D-size sheet of media.
Because the carriage must travel across the media, the time it takes to print images includes the travel time for the carriage. Additionally, the mechanical components that move the carriage add to the complexity, size, and weight of the printer and are a source of noise and vibration that can be annoying to a user of the printer.
Moreover, the pens in inkjet printers require periodic alignment to ensure consistent quality in the printed image. Because the pens are mounted in separate cartridges, there is always a risk of misalignment between pens, particularly when one or more cartridges are replaced.
Prior attempts to solve the above mentioned limitations and disadvantages of multiple cartridge inkjet printers include mounting a plurality of inkjet printheads onto a wide substrate such as a multi-layer ceramic substrate or flexible substrate. Those solutions have several disadvantages.
First, expensive precision tooling is required to align the printheads to the substrate. Second, a mismatch between the coefficient of thermal expansion for the printhead and the substrate can result in thermal induced stress on the interconnect used to electrically connect the substrate to the printheads. Additionally, the mismatch can result in misalignment between the substrate and the printheads. Third, the interconnect, the materials used for the substrate, and adhesives used to attach the printheads to the substrate are subject to failures due to the corrosive effects of the ink used in inkjet printers. Forth, the inkjet pens are sensitive to temperature variations caused by waste heat from the printheads. The substrate must have a high thermal conductivity so that the waste heat can be dissipated. If the substrate has a low thermal conductivity, then the waste heat can raise the temperature of the pens resulting in an increase in the pens drop volume. Subsequently, a temperature differential exists among the printheads so that the drop volumes of the printheads can vary depending on their location on the substrate. Ideally, the thermal conductivity of the substrate and the printheads would be identical so that there is no temperature differential between the printheads resulting in consistent drop volumes among the printheads.
Therefore, there is a need for a carrier that can mount one or more inkjet printheads in alignment with one another and with the carrier and does not require expensive precision tooling to align the printheads to the carrier. Moreover, there is a need for a carrier that has a high thermal conductivity, a coefficient of thermal expansion that matches the coefficient of thermal expansion of the printheads, and is made from a material that is resistant to the corrosive effects of ink.
Broadly, the present invention is embodied in a common carrier that includes a carrier substrate having one or more pockets formed in the substrate. Each pocket includes a side profile formed in the pocket. A chip having an identical side profile that complements the side profile in the pocket is mounted to the carrier substrate by inserting the chip into the pocket. The complementary side profiles result in near perfect self-alignment between the chip and the carrier substrate.
The carrier substrate and the chip can be made from identical materials. The side profiles can be formed by etching the carrier substrate and the chip along identical crystalline planes. The problems associated with thermal mismatch and low thermal conductivity are solved by using identical materials with a high thermal conductivity for the carrier substrate and the chip. Furthermore, the materials for the carrier substrate and the chip can be selected to be resistant to the corrosive effects of ink. The problems associated with alignment between the carrier substrate and the chip are solved by etching the pocket and the chip along identical crystal planes.
In one embodiment of the present invention, the carrier substrate and the chip are made from a single crystal semiconductor material and the side profiles are formed by etching the side profiles along identical crystal planes.
In another embodiment of the present invention, the side profiles are formed by an anisotropic etch process.
In one embodiment of the present invention, the carrier substrate and the chip are made from a single crystal silicon material and the side profiles are formed by etching the side profiles along identical crystal planes of the single crystal silicon.
In another embodiment of the present invention, the single crystal silicon for the carrier substrate and the chip has a (100) crystalline orientation and the side profiles are formed by etching along a (111) crystalline plane of the carrier substrate and the chip.
Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the present invention.